The cell cycle core serves the investigators in this PO1 by providing facilities, expertise and technical support for the cellular level analysis of cell cycle progression. The core is designed to make use of the existing University of Pennsylvania Abramson Cancer Center Flow Cytometry facility located in 297 John Morgan Building with satellite facilities in 762 BRB II/III and 304F Johnson Pavilion as well as to provide common access for all investigators to epifluorescent microscopy and videomicroscopy and image analysis equipment located in Dr Muschel and Dr Yen?s labs. The Flow cytometry facilities house four FACSCalibur and one FACSort 6 parameter, 4 color cytometers, a FACStar plus (FSP) 8-parameter 5 color flow cytometer, a FACS Vantage SE 8 parameter, 6 color high-speed sorter, a new digital FACSDiVa 10 parameter/8 color high speed sorter, and three FACScans tabletop analyzers. The Epifluorescence/videomicroscopy/image analysis facilities house a Leica DMIRBE and Zeiss axioskop and Nikon TE300 epifluorescent research microscopes with image acquisition using Hamamatsu and Snapper CCD cameras. Additional capacity is furnished by an Eppendorf semi-automated microinjector for maniplulating function and expression of cell cycle regulatory proteins. Openlab image analysis software and Macintosh G4 computers are linked to this equipment for data analysis and storage. The core includes a director who is responsible for interfacing with the principal investigators, integrating the various componentsof the core, overseeing the technical support and conducting Q/A and utilization reviews. Technical support personnel provide standardized sample and reagent preparation. These support personnel also help with equipment usage and training new investigators.